The present invention relates to a method of preventing the browning or darkening of fish such as small fish or fry, for example, young sardines, eels, and sand lances, and also a method of obtaining fish free of the browning or darkening from the browned or darkened fish. The present invention also relates to foods seasoned with various seasonings such as specially seasoned sea-urchin eggs, which keep the commercial value thereof and free from dripping of fish meat or body for a long period of time, from raw small fish such as the youngs of fish and fry, e.g., young sardines, eels, and sand lances, and a method of producing them. In addition, the present invention relates to fish prevented from the browning or darkening, or those recovered from the browning or darkening.
Fish such as young sardines (the young of fish, e.g., anchovies, pilchards, Japanese icefish and eels) and sand lances were hitherto caught on a fishing boat in a fishery, then usually put on the market, and treated by removing stains and foreign matters from them, washing them with tap water, sea-water or the like, draining and packing them and freezing and storing them in a factory, or they were shipped while they were kept cold. In some cases, the drained fish were treated with hydrogen peroxide, chlorine or the like, boiled, drained again, packed and shipped.
On the other hand, in the production of dried young sardines, the young sardines are packed in ice on the ship, and then washed with water if necessary, boiled with hydrogen peroxide (in 1 to 8% salt water), drained and dried in a factory or the like.
It is known, however, that when small fish such as young sardines are caught and dead, their body surfaces become brown or darkened, and the original color such as whitish tone of the fish rapidly disappears. Supposedly, this phenomenon occurs because bacteria in sea water are attached to the surface of the dead fish body to start the decomposition of the protein of the body surface. It is generally considered that because the cells per se of the youngs of fish and fry which are rapidly growing are soft, they are easily decomposed or deteriorated by bacteria. Although it is eagerly demanded to eat as fresh as possible fish free from browning or darkening, it has been impossible until now to provide fish kept fresh and also kept from the browning or darkening.
The methods employed in the prior art include a method wherein fish caught in a fishery are transported to a factory as soon as possible and boiled there as soon as possible to prevent them from the browning or darkening; a method wherein the fish are treated with hydrogen peroxide or chlorine; and a method wherein the fish are colored with a colorant so that they look fresh even after they were browned or darkened. However, in fact, these methods are yet unsatisfactory for the following reasons: they cost much labor; they cause problems of the environmental pollution; and when the colorant is used, the colored fish are yellowed during the storage for a long period of time.
It is known, however, that when dead, small fish such as young sardines are left for even a short time, the deterioration starts on the surface of the fish body to gradually cause the body dripping and to lose its original shape. As a result, the fish bodies become thin or they are broken to seriously lower the commercial value thereof. Supposedly, this phenomenon occurs because bacteria in sea water are attached to the surface of the fish bodies to start the decomposition of the protein on the body surface. It is generally considered that because the cells per se are soft particularly in the young of fish and fry which are rapidly growing, they are easily decomposed or deteriorated by bacteria.
For the reasons described above, the small fish are treated with hydrogen peroxide or chlorine, washed with water, packed, frozen and put on the market as rapidly as possible after they are caught. However, as the time passes after the thawing, the body dripping and the losing of the shapes of them are accelerated, and also the body surface is browned or darkened. In fact, the commercial value of them is seriously lowered in a short time of about 4 to 5 hours. These problems were not yet been solved. Although it was tried to distribute a food, prepared by mixing raw, small fish such as young sardines with a paste of seasoned sea-urchin eggs, by transporting the food in frozen state and selling it while it is thawed in a shop according to the frozen chilled system, such a system was impossible on the market because the body dripping of the fish is caused and the shape of the bodies thereof is changed to such an extent that the original shape could not be recognized while they are sold in the chilled state for 3 to 4 days after the thawing.
Many of small fish such as young sardines were imported until now. The small fish to be imported to Japan are usually obtained by transporting these fish caught on a fishing boat in a fishery of a foreign country through, for example, a market, then treating them by removing stains and foreign matters from them, washing them with sea water or the like, and draining, packing and freezing them in a factory. The small fish are also imported in the form of dried fish.
It is known, however, that when the captured small fish such as young sardines are dead, the body surfaces of them are discolored and become brown or dark as described above, and the original color such as whity tone of the fish rapidly disappears. It is also known that when a fresh small fish is left for even a short time, the deterioration starts on the surface of the fish body to gradually cause body dripping and to lose its original shape. As a result, the fish body becomes thin or it is broken to seriously lower the commercial value thereof. Thus, imported small fish have usually been browned or darkened in the course of the treatment in foreign countries, and they are imported in the browned or darkened state.
In addition, the discoloration of the small fish is caused or further accelerated by drying. As a result, the imported small fish generally have lost their fresh color and they have been discolored and browned and, in an extreme case, they have been darkened. In the course of an additional treatment or further transportation or storage of the imported small fish in Japan, the discoloration further proceeds in general to make the commercial value of them lower.
In the prior art, such browned or darkened, imported small fish were treated by a method wherein they are bleached with a bleaching agent such as chlorine or hydrogen peroxide. When the degree of the browning or darkening is low, such a color is masked by the treatment with a colorant to fade the brown or dark color. However, as the period of the storage or transportation after the treatment becomes longer, the browning or darkening is inclined to further proceed and the commercial value of the fish is lowered before the consumers get them. When the degree of the browning or darkening is high, the fish could be no more treated at all in the prior art.